There has been conventionally known a linear segmented polyurethane-urea elastomer manufactured by reacting a diamine compound or a mixture of a diamine compound and a secondary monoamine, with a polymeric intermediate (U.S. Pat. No. 3,557,044).
U.S. Pat. No. 3,557,044 disclosed manufacture of polyurethane-urea elastomer comprising reacting a diamine compound and a secondary monoamine with a polymeric intermediate. However, this patent does not pay attention to the thermosetting ratio as taught in the present invention, but intends to obtain a polyurethane-urea elastic yarn having superior mechanical properties even from polymers having low viscosities.
The conventional polyurethane elastic yarns include, for example, a polyurethane elastic yarn obtained by using a diol as a chain extender for a polymeric intermediate and a polyurethane-urea elastic yarn obtained by using a diamine as a chain extender for a polymeric intermediate. While the former generally shows 70% or more of a thermosetting ratio and is superior from this aspect, it is inferior in mechanical properties such as tensile recovery under heating and elongation. In contrast, the latter is generally superior in mechanical properties such as tensile recovery under heating and elongation, whereas it shows low thermosetting ratio.
A well-known use of the polyurethane elastic yarn is for panty hose, for which polyurethane-urea elastic yarns obtained by dry spinning polyurethane-urea elastomers having been frequently used. In recent years, elastic yarns have been increasingly used for forming the leg part of panty hoses. As mentioned above, however, polyurethane-urea elastic yarn has a low thermosetting ratio, which causes disturbance in knit fabric caused during a setting step in panty hose manufacture to result in defective appearance of the product. To avoid this, a polyurethane elastic yarn has been used which is manufactured using a diol for chain-extending a polymeric intermediate. Yet, such polyurethane elastic yarn has insufficient mechanical properties such as tensile recovery under heating.